Disruption of the olfactory system has been well-described in patients with schizophrenia; with psychophysical deficits, smaller olfactory bulb/cortex and reduced posterior nasal volume in patients being reported. These findings, however, could be either neurodevelopmental or degenerative in origin. In contrast, alterations of sinus volume are indicative of disruptions occurring during a specific window of embryologic development. Specifically, the 1) maxillary and 2) ethmoid sinuses develop prenatally and the 3) frontal and 4) sphenoid sinuses develop postnatally. As such, differential development patterns of the sinuses can allow us to probe more precisely where in the developmental process the neurodevelopmental first hit occurs in patients at-risk for psychosis and in patients who have already become ill. We will obtain high-resolution CT scans of the paranasal sinuses in 15 clinical risk (CR) subjects, 15 early psychosis (EP) patients, and 30 matched healthy-comparison subjects. Volumetric assessment of the sinuses will be performed along with standardized assessments of psychophysical olfactory performance and quantified assessments of nasal/palate volume and geometry. Our working model is that disruptions of sinus morphology and volume reflect abnormalities in embryological development that may in turn be used as a risk marker for the later onset of psychosis.